The totals shown for each sharing button comes from the other services themselves – Facebook, Twitter, etc. What those services use for the total share count is the *exact* URL of the post when it was originally shared.
In your case, the posts were published prior to changing your URL from using http to https. Since the exact URL of the posts has now changed, the counts will have been reset to zero.
Also, since the count data lies with each service and not on our servers at WordPress.com or within Jetpack itself, there’s no way for us to merge or update those totals on our end.
I hope that clarifies things. Marking this as resolved.
